Rheostat.



Nd. 755,827. PATENI'ED MAR. 29, 1904. W. G; YATES &: P. ZIMMER.

RHEOSTAT.

APPLICATION FILED JULY 25. 1903.

NO IODEL.

Inventors. W1 Hiam C. Yates.

Paul Z imme; 7

UNITED STATES Patented March 29, 1904.

P T T ()FFICE.

WILLIAM C. YATES AND PAUL ZIMMER, OF SOHENECTADY, NEW YORK, ASSIGNORS TOTHE GENERAL ELECTRIC COMPANY, A CORPORATION OF NEWYORK.

SPECIFICATION forming part of Letters Patent No; 755,827, dated March29, 1904.

Application filed July 1903. Serial No. 166,949. (No model.)

To all whom it may concern:

Be it known that we, VVTLLIA 'C. YATES and PAUL ZIMMER, citizens of theUnited States,re siding at Schenectady, in the county of Schenectady,State of New York, have invented certain new and useful Improvements inRheostats, of which the following is a specification.

This invention relates to rheostats; and its object is to provide acompact device by which a wide range of resistance can be regulated insmall gradations. In devices of this kind heretofore made the entireresistance has been cut into circuit insmall' steps either by employingagreat number of contact-studs connected to the resistance or by havingtwo sets of resistances and mechanism so arranged that after a definitenumber of small units have been cut into circuit a further movement ofthe rheostat-handle will first substitute a' single large unit for thesmall ones and then cut the small units in again progressively. By ourinvention the resistance is cut in in large units until an amountapproximating the desired amount has been obtained and then in smallsteps to get the exact amount re-,

quired. In this way a very large amount of resistance can be cut intocircuit quickly and by a small movement of the rheostat-handle, and whennear the desired amount the adjustment may be accurately completedwiththe small units.

In carrying out our invention we provide two sets of resistancesconnected to contacts til an amount of resistance approximatingthedesired amount is obtained Without affecting the resistance of the setof small units. brush cooperating with the studs connected to the smallunits can then be manipulated to The any unit of the other and meansoperated by a single handle for increasing .or decreasing the resistanceof either set without affecting the resistance of the other set.

It further comprises other featuresof novelty, which will be definitelyindicated in the appended claims.

In the accompanying drawings, which illustrate one embodiment of ourinvention, Figure 1 is a perspective view of our improved rheostat,having the lower part broken away; and Fig. 2 is a diagrammatic view ofthe arrangement of the resistances and the circuit connections.

In the drawings, 1 represents a base-plate of soapstone or otherinsulating material on which are mounted two sets of studs 2 2 and 3 3,preferably arranged in two'concentric circular rows. of eachrow areresistance units, which may be iron grids, coils of wire, or resistancesof any other desired form mounted in a box-like structure 4, havingperforated side walls secured to the bottom of the base-plate.

circle are of much lower resistance than those connected between thestuds of the outer circle, the function of the former being to subdivideinto numerous small steps any unit of the outer series. At the center ofthe circles of studs is mounted a shaft 5, rotated by a handle 6.Surrounding the shaft and lagged fast to the base-plate isa collar 7,having a peripheral groove forming a bearing for a hub 8, carrying anarm 9. Secured to the outer end of this arm, but insulated therefrom, asshown in Fig. l, is a bridging contact Connected between the studs Theunits connected between the studs of the inner sistance are stillmaintained.

brush 10, adapted to cross-connect the contact-studs of the two circularrows. Above the collar 7 on the shaft 5 and rigidly secured to the shaftare two other collars 11 and 12, one of which has two fingers 13 and 14.One of these fingers carries a brush 15, arranged to bear on the studsof the inner circle and electrically connect them with the shaft 5, andboth of the fingers cooperate with a lug 16 on arm 9 to move the brushin either direction over the contact-studs. In'the outer row of studs isa stop 17, and from the stud adjoining this stop around the circular rowthe resistance units are arranged in series and connected to thecontact-studs, as shown in Fig. 2. In the preferred form of ourinvention all the studs 01 the inner circle are connected together bythe small resistance units, there being no break in the continuity ofthe circuit around the entire circle. Mounted on the base-plate are twobinding-posts 18 and 19, the former being connected to the first stud 22of the outer row by wire 20 and the latter to the shaft 5 by wire 21.

In Fig. 2 of the drawings we have shown the rheostat as used to regulatethe field-current of a dynamo-electric machine; but it is obvious thatit may be used in numerous other ways. i

The operation of the device is as follows: With the brush 10 on thefirst stud 22 of the outer series and stud 23 of the inner series andthe brush on this same stud 23, the arm 9 being bent laterally to permitsuch a movement, there is no resistance in the circuit, and the path ofthe current is from bindingpost 18 over wire to stud 22, brush 10 tostud 23, brush 15 to shaft 5, and wire 21 to binding-post 19. From thisposition movement of the handle in a clockwise direction moves brush 15from stud 23 around to the stud diametrically opposite, in whichposition the current divides at stud 23 and flows in two parallelcircuits around the inner circle of resistance units to the brush 15 andthence out as before. The resistance in circuit is then one-fourth ofthe entire resistance of the inner circle, as there are two parallel"circuits, in each of which one-half of this resistance is included. henin this position, the finger 1 1 abuts against lug 16 on arm 9, and afurther movement of the handle .in the same direction will move brush 10over the outer row of studs, cutting in in series one of thehighresistance units for each stud passed over, but not changing theresistance of .the inner circle, as the two parallel paths of equal re-WVhen the operator has moved the brush 10 until it bears on a certainstudas, for instance, stud 21-he may find that he has almost reached therequired amount, and when he moves the brush to the next stud 25 he mayfind that he has cut in too much resistance. Under such circumstancesthe natural impulse would be to turn the handle in the oppositedirection, but in doing so the position of brush 10 would not bechanged, the only eilect of such movement being to bring the brush 15around over the studs of the inner circle toward the inner end of thebrush 10. his decreases the resistance of one and increases theresistance of the other of the two parallel circuit-s around the innercircle, the effect of which is to decrease in steps the total resistancebetween the inner end of brush 10 and brush 15. The. inner circle ofresistance may be so proportioned that a movement of brush 15 from thestud diametrically opposite that on which the inner end of brush 1Obears to the stud on which brush 1O bears reduces the total resistancein circuit in steps by the same amount that included between twoadjacent studs of the outer circle. The operator is thus enabled toobtain the exact amount of resistance required. Should it be desired todecrease the resistance in circuit, the handle is turned in acounterclockwise direction and the resistance de creased in small stepsuntil finger 13 abuts against stud 16, and then inlarge steps. 'hen theoperator finds that in going from one step to the next he has reducedthe resistance too much, his impulse again is to turn handle 6 in theopposite direction, in 'doing-wh' -h he does not affect the position ofarm 9, ant merely moves brush 15 over the contacts 3 3. This transfersthe small resistance units from one of the parallel circuits to theother, increasing in small steps the total resistance between brush 10and brush 15. To return the brush to its original position, a continuedcounter-clockwise movement of the handle brings linger 13 against lug 16and pushes arm 9 back over the contacts to its original position.

Many variations can be made in our device--- such, for instance, asbreaking the continuity of the circuit through the small resistanceunits between stud 23 and the stud next preceding it or at some pointdepending upon the position of arm 9, in either of which cases therewould be only one path through the smaller resistances; but all suchvariations we consider to be within the spirit of our invention.

What we claim as new, and desire to secure by Letters Patent of theUnited States, is

1. A rheostat provided with a series of resistance units, a contactdevice for cutting them into circuit progressively, a handle for saiddevice, and means operated by said handle for varying the resistance atintermediate points of the series by fractional parts of a unit withoutaffecting said contact device.

2. A rheostat having a plurality of coarse resistance-steps, a pluralityof liner steps, a handle, and means operated thereby for regulating theresistance on either set of st :ps at will at different points of"adjustment.

3. A rheostat having a plurality of resist ance units, a handle, andmeans operated. there by for regulating the resistance in circuit inrelatively large steps until an amount approximating the desired amounthas been obtained, and then in smaller steps for more exact regulation.

4:. A rheostat having a variable resistance, a handle for cutting theresistance into or out of circuit in steps, and means operated by saidhandle for subdividing the steps at different points of the resistanceinto a number of smaller steps if desired.

5. -A'rheostat having two sets of resistances connected to two rows ofstuds arranged in concentric circles, and means for regulating theresistance of either set without affecting the resistance of the otherset.

6. A rheostat having a plurality of resistances, an operating device,means operated by a movement of the device for regulating the resistancein circuit in steps, and means operated by a reverse movement forregulating the resistance in circuit in smaller steps.

7. A rheostat having a plurality of resistances, a rheostat-arm, meansoperated by a movementof said arm in one direction for regulating theresistance in circuit in steps, and means operated by a movement in theother direction for regulating the resistance in circuit first in smallsteps and then in larger steps.

8. A rheostat having a series of resistances arranged in steps, anoperating device for cutting them into and out of circuit, means0perated by a movement ofthe device in one direction for regulating theresistance in circuit in steps, and means operated by movement in theother direction for subdividing a step of the resistance into a numberof smaller steps.

9. A rheostat having two concentric rows of studs, resistance connectedbetween the studs of each row, a handle, a contact device operatedthereby, and means whereby movement of the handle in one directionincreases the resistance in large steps and in the other directiondecreases the resistance in small steps.

10. A rheostathaving two concentric rows of studs, resistance connectedbetween the studs of one row, resistance of less value connected betweenthe studs or the other row, a handle,means operated thereby forregulating the resistance in steps, and means for subdividing any stepinto a plurality of smaller steps. 1

11. A rheostat having resistances diflering in value, anoperating-handle for regulating the amount of resistance in circuit, andmeans whereby movement of the handle in one direction regulates theresistance of one value and movement in the other direction regulatesthe resistance of a difierent value.

12. A rheostat having two concentric rows of studs, two sets ofresistances, one set connected to the studs of each row, a' handle, andmeans operated thereby for regulating the resistance of either setwithout affecting the resistance of the other set.

13. In a rheostat, two concentric rows of studs to which the resistanceis connected, two switch-arms bearing on the contacts, anoperating-handle, and means whereby movement.

of the handle moves one arm to a predetermined position and then movesboth arms simultaneouslye 1 1. In a rheostat, two rows of studs to whichthe resistances are connected, a contact-arm cross-connecting the tworows, a contact-arm adapted to bear on the studs of one row, and meanswhereby one of said arms may be moved independently of the other.

15. In arheostat, two rows of studs to which the resistances areconnected, a contact-arm cross-connecting the two rows, a contact-armadapted to bear on the studs of one row, and means for moving saidcontact-arms together or one independently of the other.

16. In a rheostat, a row of contact-studs, resistance connected betweeneach stud and two other studs forming a closed circuit, two contacts,means for moving them over the studs in a fixed relation to each other,means whereby said movement regulates a resistance in series with saidcontacts in steps, and means whereby one of the contacts can be movedindependently of the other.

'17. In a rheostat, two parallel circuits through resistances, avariable resistance in series with the parallel circuits, and means fortransferring resistance from one of said parallel circuits to the otherat any step of the variable resistance.

In witness whereof we have hereunto set our hands this 2 1th dayof July,1903.

.WILLIAM C. YATES. PAUL ZIMMER.

Witnesses:

BENJAMIN B. HULL,

HELEN ORFORD.

